Optical Element, Light Diffusing Element, and Image Display Apparatus

3. The light diffusing element of claim 2 , wherein the light diffusing structure comprise microlens arrays.

4. The light diffusing element of claim 2 , wherein the light diffusing structures and the micro convexo-concave structure are made of plastic material.

5. An image display apparatus, comprising: one or more light sources emitting visible light in a wavelength range of from a wavelength λS to a wavelength λL, the wavelength λL being greater than the wavelength λS (λL>λS); an original image generator to generate a two-dimensional original image using a light flux having directivity coming from the one or more light sources; the light diffusing element of claim 2 , to diffuse the light flux coming from the original image generator as a diffused light flux having directivity; a focusing optical system that the diffused light flux enters, to focus an enlarged image of the two-dimensional original image; and a reflector, disposed on an optical path between the focusing optical system and the enlarged image, to reflect a focus light flux to an observer.

6. The image display apparatus of claim 5 , wherein the one or more light sources comprise a semiconductor laser light source.

7. The image display apparatus of claim 6 , wherein the one or more light sources comprise three semiconductor laser light sources, each emitting light of three wavelength of λ2 and λ3 that can generate a color image, and the wavelength of λS, λ1, λ2, λ3, and λL satisfying a relationship of condition (7) λS≦λ1<λ2<λ3≦λL.

8. The image display apparatus of claim 6 , wherein an oscillation wavelength λ, of the one or more light sources varies in a range of λS<λ<λL.